Conventionally known as a floor structure of a railcar is a structure (hereinafter referred to as a “sub-floor structure”) in which: a floor pan having a concave cross section is arranged between cross beams of an underframe; and a heat insulating material or the like is provided inside the floor pan. Further, proposed is a floor structure (for example, PTL 1) in which: a corrugated plate and a floor receiver are arranged in the underframe; and a heat and sound insulating material is provided between the corrugated plate and the floor plate.
According to the floor structure of PTL 1, since the corrugated plate is arranged at a position lower than upper surfaces of the cross beams and higher than a lower surface of the underframe, a buckling strength of the floor structure can be improved, and the upper surface of the floor can be lowered.